Electrical circuit breaker



Patented May 3, 1949 ELECTRICAL CIRCUIT BREAKER Joseph F. OBrien, Lebanon,

and John B. Cataldo,

Annandale, N. J., assignors to John B. Pierce Foundation, New York, N. Y., a corporation of New York Application March 4, 1947, Serial No. 732,308 4 Claims. (Cl. 200-116) This invention relates to electrical circuit breakers for protecting electric circuits against overload, and constitutes an improvement on existing devices of the type.

It is an object of the invention to provide an electrical circuit breaker which is very simple and compact in construction, yet positive and completely eiective in operation.

It is an object to provide the same with means clearly indicating to an observer when the circuit is broken.

It is a further object to provide means for quickly and easily resetting the device following any circuit breaking action thereof.

These and further objects and features of the invention will be fully explained in 'the following detailed description of the preferred specific embodiments illustrated, by way of example only, in the accompanying drawing.

In the drawing:

l is a side elevation. of the device;

Fig. 2 is a central vertical section, showing the circnit in. its normally closed condition;

Fig. 3 is a corresponding View, out showing how the device operates to hreak the circuit overload;

4 is another corresponding View, lout showing 'the device as it appears following its circuithreaking operation;

Fig. 5 is a similar View showing how the circuit is reclosed and the device re-set from its thrown positions of Figs, 3 and 4;

Fig. 6 is a transverse section taken on the line G--6, Fig. 2, somewhat reduced in size; and Fig. 7 is a similar transverse section taken on the line 'l2-T, Fig. 2.

Referring now to the drawing: the operative mechanism of the preferred form illustrated is, housed in a casing I0, advantageously molded from an insulating plastic in two complementary longitudinal sections held together by spring wire hoops II which snap into circumferential receiving grooves, see Fig. l. A neck Illa, through which extends a manually controlled re-set push button I2, may be externally threaded as shown for convenient installation of the device in a panel or other supporting structure. A disc I3,

Fig. 2, of insulation serves to close the opposite end of the casing I0 and to carry the external electric terminals of the device.

The device is arranged to be connected across an electric load circuit in such manner as not to interfere lwith the normal functioning thereof except at such times as overload is manifest, whereupon the device acts to break the circuit so the excessive load will not be enough to cause damage.

As illustrated, the electric terminals I4 and I5 afford means for connecting the device in a load circuit to be protected from damage by electrical overload.

Within the casing I 0, a throw-rod I1 is supported longitudinally by means of partition elements i8 and I9. Such throw-rod I'I passes through the partition elements, having bearing therein for sliding movement. @ne end portion Ila of l such throw-rod is disposed within a corresponding receiving passage, which extends completely through the push button i 2, longitudinally thereof, said end stoppin-g short of the open outer end of the passage in the unthrown or norm mal position of the rod, see Fig. 2. As shown the rod is electrically conductive.

The opposite end of the throw-rod l1 is formed as an electrical Contact, preferably by having a disc lib of silver or other suitable material secured thereto. A second electrical Contact 253, mounted on an electrically conductive resilient arm il, cooperates therewith in the completion of the load circuit normally maintained closed by the device. The arm 2i is anchored, preferably to the partition element I8 which is of insulation.

The throw-rod Il is normally maintained in its unthrown or circuit closing position of Fig. 2 by means of a mechanical latching arrangement, and is forcibly thrown to its circuit-breaking pom sition of Figs. 3 and 4 by resilient means which become eiective upon the unlatchlng of the rod.

The resilient means advantageously taire the form of a spring disc 22, anchored circumferentially in the casing I0, and an auxiliary or booster coil spring 23. The latter is disposed between the spring disc 22 and a circumferentially shouldered portion 24 formed intermediate the length of throw-rod I1, the spring disc thereby acting on the throw-rod through the intermediacy of the coil spring.

The mechanical latching arrangement here comprises a latch arm 25, pivoted at one end to the partition element I9 and extending longitudinally within the casing into the vicinity of partition element I8. As illustrated in Fig. 7, partition element I9 is advantageously apertured deeply from its periphery and provided with stub projections for receiving and journaling the opposite ear formations 25a, 25a of latch arm 25.

A latch linger 25h extends from latch arm 25, being advantageously an intermediate portion thereof which has been struck outwardly as shown. It lies in the vicinity of the shouldered maintained long portion 24 of throw-rod |1, and is arranged to engage and latch under a flanged part 24a of such shouldered portion by reason of the action of a spring 26 pressing the latch arm, as a whole, inwardly.

Secured to the partition element I8 and extending therefrom so that its free end lies adjacent the free end of the latch arm 25 is a slightly curled bi-metal thermo element 21 encircled by an electric heating coil 28. Such heating coil is electrically connected in series with the electric terminals I4 and I5, the series circuit including, however, the separable electrical contacts |1b and 2D. As shown, the circuit comprises a wire 29 electrically connecting the terminal I4 to one end of the heating coil 28 through the intermediacy of a conductive stud 30 which passes through the partition element I8, a. Wire 3| electrically connecting the other end of the heating coil 28 to the throw-rod I1, and a wire 32 electrically connecting the resilient arm 2| (which carries the movable contact 22) to the terminal I5. Accordingly, current may fiow through the series circuit so long as the contacts I1b and 20 are in make or closed position. Should a dangerous overload occur in the supply circuit, however, heater coil 28 will cause bi-thermo element 21 to uncurl against latch arm 25, moving it outwardly on its pivot axis to withdraw latch finger 25h from its position which latches throw-rod I1 against the throwing urge of spring disc 22 and coil spring 23. Under such circumstances, said spring disc 22 and coil spring 23 will throw throwrod |1 to the limit position of Fig. 3, thereby breaking the circuit at the contacts |1b and 20. Shouldered portion 24 of the throw-rod, it will be noted, serves as a limit stop determining such limit position by abutment against I2a of the push button. The push button I2, then, in effect becomes itself a limit stop for the throw-rod.

In the abofm-described circuit breaking action of the device. it should be noted that resilient arm 2| carrying the electrical contact 20 is held in normal position when the throw-rod I1 is thrown, so that contact 2U does not follow electrical contact |1b. This is conveniently accomplished by a rigid pin 34, preferably of electrical insulating material, which extends longitudinally within the casing I from the back flange I2a of push button I2 to abutment against the resilient arm 2|, passing through suitably provided apertures in the partition elements I9 and I8.

To reset the device following the circuitbreaking action thereof, it is only necessary to press push button I2. That resetting is necessary is made readily apparent to an observer by the fact that the end of throw-rod I1 is substantially flush with the outer end-of the push button. Such end of throw-rod I1 may be colored distinctively and brightly, the better to attract attention.

Push button I2 works against a return spring 35, and the rigid pin 34, as here illustrated, works against a return spring 36. Pressing of push button I2 following circuit-breaking action of the device changes the positions of the parts in the manner indicated by the differences between Figs. 4 and 5. That is to say, throw-rod I1 is pushed inwardly so that latching finger 25h snaps back into latching position under keeper flange 24a. At the same time, rigid pin 34 pushes resilient arm 2| so that it moves electrical contact 2U out of range of the re-positioned electrical contact |117, thereby preventing re-establishment of a closed circuit until the device is completely 4 relatched and the push button returned to its normal position, as in Fig. 2.

It will be noted that the device has a trip-free action. That is to say, the circuit may be broken manually without disturbing the overload protectivc` mechanism. By pressing push button I2 at any time that the circuit is closed, the circuit may be opened, and it may be held open for as long a time as the push button is continued to be pressed, see Fig. 5. Release of the push button will, of course, result in re-closing the circuit.

We claim:

l. In an electrical circuit breaker, throw means carrying an electric contact; movable supporting means carrying a second electric contact f or make and break with said first contact; latch means normally maintaining said throw means in fixed position relative to said supporting means so that the said contacts are closed; resilient means operative to actuate said throw means in a direction away from said second contact; thermostatic means responsive to electrical overload for positively tripping said latch means, said means being disposed in the electric circuit governed by said contacts, and being effective to release said latch means upon a given condition of electrical overload in said circuit; a push button associated with said throw means and serving as a limit stop therefor in its thrown position so that pressing of said push button will re-set said throw means in its normal latched position; and means mechanically connecting said push button with said movable supporting means so that pressing of the push button will move said second contact out of rangeof the first.

2. An electrical circuit breaker comprising a casing; a push button installed in said casing for manual operation exteriorly thereof; a throw-rod mounted for longitudinal movement within the casing, said throw-rod having one end slidably associated with said push button and a portion arranged as a limit stop for abutment against said push button in the thrown position; resilient means constantly urging said throw-rod towards the said limit position; latch means normally holding said throw-rod against the urge of said resilient means; an electrical contact carried by the other end of said throw-rod; a second electrical contact carried by movable supporting means, said second contact being in break relationship with said contact carried by the throwrod when said throw-rod is released by said latch means, and normally in make relationship with said contact when said throw-rod is held by said latch means; means responsive to electrical overload, said means being disposed in the electric circuit governed by said contacts, and being effective to release said latch means upon a given condition of electrical overload in said circuit; and means mechanically connecting said push button with said movable supporting means so that pressing of the push button will move said second contact out of range of the first.

3. The combination recited in claim 2 wherein the movable supporting means carrying the second electrical contact is a resilient arm, the mechanical connecting means between push button and said supporting means is a rigid pin, and said rigid pin serves to support said resilient arm in fixed positon when electrical overload in the circuit causes said throw-arm to be thrown.

4. The said combination recited in claim 2 wherein that said end of the throw-rod associated with the push button projects into the field of vision of an observer when the throw-rod is in 5 6 thrown position, and is colored distinctively to at- UNITED STATES PATENTS tract attention.

JOSEPH F. O'BRIEN. Number Name Date JOHN B. CATALDO. 1,766,965 Thomas June 24, 1930 5 2,150,635 Rodgers Mar. 14, 1939 REFERENCES CITED 2,325,650 Baxter Aug. 3, 1943 The following references are of record in the me of this patent: 

